The contemporary carbon budget for the atmosphere requires
a large "missing" carbonsink to balance anthropogenic carbon inputs. We investigated
climatic effects on carbon exchanges between the atmosphere and the undisturbed
biosphere and assessed the possible contribution of climate variability
to the carbon sink. Empirical models and global temperature and precipitation
data sets were used in the study. It was found that climateperturbations during 1940-1988 caused considerable variations
in plant productivity andsoil respiration. The different sensitivities of the
fluxes to climate perturbations led to a significant carbon accumulation
in the biosphere. The cumulative carbon sink for theperiod 1950-1984 (~20±5 GtC or 10**12 kg C) was
predominantly located in mid-latitudesin the northern hemisphere (30-60°N) and could amount
to half of the missing CO2 sink as derived from deconvolution analyses.
Our results indicate that climate variations have unequal impacts on biospheric
carbon fluxes from different ecosystems and imply that caution must be
exercised in generalizing in situ observations to the globe.